Transplantation of virally transduced cells into the dermis of immunocompetent and immunodeficient (SCID) mice to determine gene expression profile and differential donor cell survival

Cell therapy and bioengineering hold great promise as therapeutic approaches using cells and cell-derived factors to treat various pathologic or trauma-induced states. One possible application is the transplantation of cells into wounded tissue to help regulate tissue repair. Cells engineered for optimal wound healing may help to minimize scarring following surgery or to enhance the rate of healing of chronic wounds. The purpose of the current study was to determine the effect of a viral insert, the LacZ-bearing, first generation adenovirus AdRGD, on the survival of dermally transplanted murine skin allogenic fibroblasts. The LacZ insert facilitated quantitation of both cell survival and gene expression and was used here to measure viable cell number. In addition to bearing the LacZ marker, the AdRGD vector is capable of carrying therapeutic gene inserts, so this study tested the feasibility of gene therapy for wound healing. Murine skeletal muscle PP6 (i.e., Pre-Plate 6) myogenic stem cells served as an alternate donor cell type. Cells were labeled with the LacZ-bearing AdRGD adenovirus vector and injected (50,000 cells/site) into the dorsal skin of adult normal, immunocompetent mice as well as in immunodeficient SCID mice. Skin biopsies were taken on days 0, 1, 2, 3, and 7 post-transplant, and assayed for LacZ expression. Soon after transplant (day 1), cell numbers underwent a transient decrease, but by day 2 post-transplant they were present in appreciable numbers. Between days 2-7 post-transplant, both allogenic fibroblasts and PP6 myogenic stem cells maintained survivability in similar numbers. Further, survival of transplanted cell types was similar in both normal, immunocompetent as well as SCID mice during this time period. There were no signs of acute inflammation or rejection in any of the samples. This study shows that AdRGD-transduced cells are not immunogenic in the mouse skin model and the cells show similar survival for the first 7 days post-transplantation independent of the cell type or immunocompetence of the host.